1. Field of the Invention
The present invention relates to a working cylinder actuated by a pressure medium. More specifically, the invention relates to a compact working cylinder utilizing a tensioning member which has a continuous circumference.
2. Description of the Prior Art
The prior art is characterized by the device shown in West German Patent No. DE-OS 24 04 244, also shown in FIG. 1 herein. The device features a cylindrical tube, in which a piston with circular cross-section moves under seal. A tension member is mounted at the piston faces, which are directed away from each other. The tension member is designed as a flat belt, and is passed, under seal, out of the front ends of the cylindrical tube, which are also facing away from each other. The seals for the rectangular belt are generally of a "wiper" type design.
One disadvantage of the prior art cylinder is its height. The circular cross-section of the piston and cylinder necessitates a square cross-sectional main body, which is added to the additional height of a cam, which is slidably mounted on the top surface of the main body. An additional disadvantage of the prior art cylinder is that the rectangular cross-sectional shape of the tension member cannot be reliably sealed as it enters and exits the cylinder.
What is lacking in the art, therefore, is a working cylinder which is compact in design, notably in its height. Additionally, a hydraulically actuated working cylinder which guarantees a reliable seal of the opening for the tension member is needed.